Foliations modeling nonrational simplicial toric varieties

We establish a correspondence between simplicial fans, not necessarily rational, and certain foliated compact complex manifolds called LVMB-manifolds. In the rational case, Meersseman and Verjovsky have shown that the leaf space is the usual toric variety. We compute the basic Betti numbers of the foliation for shellable fans. When the fan is in particular polytopal, we prove that the basic cohomology of the foliation is generated in degree two. We give evidence that the rich interplay between convex and algebraic geometries embodied by toric varieties carries over to our nonrational construction. In fact, our approach unifies rational and nonrational cases.Comment: 24 pages, 4 figures, expository changes, references updated. Link to the journal http://j.mp/BatZaf; Int. Math. Res. Not. 2015 (Published online February 24, 2015

Constraints on the active tectonics of the Friuli/NW Slovenia area from CGPS measurements and three-dimensional kinematic modeling

We use site velocities from continuous GPS (CGPS) observations and kinematic modeling to investigate the active tectonics of the Friuli/NW Slovenia area. Data from 42 CGPS stations around the Adriatic indicate an oblique collision, with southern Friuli moving NNW toward northern Friuli at the relative speed of 1.6 to 2.2 mm/a. We investigate the active tectonics using 3DMove, a three-dimensional kinematic model tool. The model consists of one indenter-shaped fault plane that approximates the Adriatic plate boundary. Using the ‘‘fault-parallel flow’’ deformation algorithm, we move the hanging wall along the fault plane in the direction indicated by the GPS velocities. The resulting strain field is used for structural interpretation. We identify a pattern of coincident strain maxima and high vorticity that correlates well with groups of hypocenters of major earthquakes (including their aftershocks) and indicates the orientation of secondary, active faults. The pattern reveals structures both parallel and perpendicular to the strike of the primary fault. In the eastern sector, which shows more complex tectonics, these two sets of faults probably form an interacting strike-slip system

The Invisible Higgs Decay Width in the Add Model at the LHC

Assuming flat universal extra dimensions, we demonstrate that for a light Higgs boson the process $pp\to W^*W^* +X \to Higgs,graviscalars +X \to invisible+X$ will be observable at the $5 \sigma$ level at the LHC for the portion of the Higgs-graviscalar mixing ($\xi$) and effective Planck mass ($M_D$) parameter space where channels relying on visible Higgs decays fail to achieve a $5 \sigma$ signal. Further, we show that even for very modest values of $\xi$ the invisible decay signal probes to higher $M_D$ than does the ($\xi$-independent) jets/\gam + missing energy signal from graviton radiation. We also discuss various effects, such as Higgs decay to two graviscalars, that could become important when $m_h/M_D$ is of order 1.Comment: 6 pages, 2 figures, To appear in the Proceedings of the Les Houches Workshop 2003: ``Physics at TeV Colliders'', ed. F. Boudjem

Sterile neutrinos as subdominant warm dark matter

In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow (DW) mechanism, we investigate the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We first study how to reinterpret the limits attainable from X-ray non-detection and Lyman-alpha forest measurements in the case that sterile neutrinos constitute only a fraction fs of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the DW mechanism, we show how the X-ray and Lyman-alpha results jointly constrain the mass-mixing parameters governing their production. Furthermore, we show how the same data allow us to set a robust upper limit fs < 0.7 at the 2 sigma level, rejecting the case of dominant dark matter (fs = 1) at the ~ 3 sigma level.Comment: Minor changes; added references; version accepted for publication in Phys. Rev.

Converting NAD83 GPS heights into NAVD88 elevations with LVGEOID, a hybrid geoid height model for the Long Valley volcanic region, California

A GPS survey of leveling benchmarks done in Long Valley Caldera in 1999 showed that the application of the National Geodetic Survey (NGS) geoid model GEOID99 to tie GPS heights to historical leveling measurements would significantly underestimate the caldera ground deformation (known from other geodetic measurements). The NGS geoid model was able to correctly reproduce the shape of the deformation, but required a local adjustment to give a realistic estimate of the magnitude of the uplift. In summer 2006, the U.S. Geological Survey conducted a new leveling survey along two major routes crossing the Long Valley region from north to south (Hwy 395) and from east to west (Hwy 203 – Benton Crossing). At the same time, 25 leveling bench marks were occupied with dual frequency GPS receivers to provide a measurement of the ellipsoid heights. Using the heights from these two surveys, we were able to compute a precise geoid height model (LVGEOID) for the Long Valley volcanic region. Our results show that although the LVGEOID and the latest NGS GEOID03 model practically coincide in areas outside the caldera, there is a difference of up to 0.2 m between the two models within the caldera. Accounting for this difference is critical when using the geoid height model to estimate the ground deformation due to magmatic or tectonic activity in the calder

Convex Polytopes and Quasilattices from the Symplectic Viewpoint

We construct, for each convex polytope, possibly nonrational and nonsimple, a family of compact spaces that are stratified by quasifolds, i.e. each of these spaces is a collection of quasifolds glued together in an suitable way. A quasifold is a space locally modelled on $\R^k$ modulo the action of a discrete, possibly infinite, group. The way strata are glued to each other also involves the action of an (infinite) discrete group. Each stratified space is endowed with a symplectic structure and a moment mapping having the property that its image gives the original polytope back. These spaces may be viewed as a natural generalization of symplectic toric varieties to the nonrational setting.Comment: LaTeX, 29 pages. Revised version: TITLE changed, reorganization of notations and exposition, added remarks and reference

Keeping watch over Colombia’s slumbering volcanoes

The Volcanological and Seismological Observatories of Manizales, Pasto and Popayan (Colombian Geological Survey) monitor and study the active volcanoes of Colombia using seismological, geodetic, geochemical and other techniques. Since 2009, permanent GNSS stations have been installed to complement classical geodetic measurements (e.g., tilt, EDM). At the moment, there are a total of 20 GNSS stations installed at Nevado del Ruiz, Cerro Machín, Puracé and Galeras volcanoes. Nevado del Ruiz has remained the most dynamic of the active Colombian volcanoes since its tragic eruption of 13 November 1985. The most significant deformation occurred between 2007 and 2012, when inflation, associated with magma migration and several small to moderate explosive eruptions in 2012 (VEI less or equal to 3), was observed. Galeras has experienced more than 25 moderate Vulcanian eruptions (VEI less or equal to 3) since 1989. In particular, the deformation network detected significant signals associated with magma migration and the extrusion of lava domes in 1991, 2005, 2008 and 2012. Puracé volcano has been the site of more than 10 minor eruptive episodes (VEI=2) in the past century, most recently in 1977. Monitoring of this volcano started in 1994. Unrest at Puracé since that time has been characterized by significant increases in seismic activity but with little or no deformation. We employ GAMIT/GLOBK to process GPS data from the monitoring network with support from the Volcano Disaster Assistance Program (U.S. Geological Survey). Additionally, differential processing is carried out using the commercial package Trimble 4D Control. Preliminary results for 2012 show no significant deformation at Puracé and Galeras volcanoes. On the other hand, the time series from Nevado del Ruiz shows a minor inflation (2-4 cm/yr) associated with the eruptive activity of 2012

COLONIZATION OF NORTHERN LOUISIANA BY THE MEDITERRANEAN GECKO, HEMIDACTYLUS TURCICUS

The Mediterranean Gecko, Hemidactylus turcicus, is known to have colonized nearly every state in the southern United States. In Louisiana, the Mediterranean Gecko has been documented in many of the southern parishes, but records for the northern portion of the state are limited. We sampled northern Louisiana parishes to document the presence of the Mediterranean Gecko. We sampled a total of 21 parishes in northern Louisiana and found geckos in 17 of those parishes, 16 of which represent new distribution records for the species. This indicates a significant range expansion of this introduced species throughout northern Louisiana. Geckos were found across a temperature range of 14.0–28.0°C and had a strong association with buildings. The species’ affinity for anthropogenic association and the continual nature of anthropogenic expansion facilitate the high vagility of this species. The result is a successful colonization throughout much of Louisiana and likely continued range expansion throughout the southern United States